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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in the evaluation of the lumbar herniated intervertebral disc (1993)
    Springer
    International orthopaedics 17 (1993), S. 241-244 
    Details
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Deux cent onze patients atteints de hernie discale lombaire, confirmée par imagerie par résonance magnétique (IRM) et représentant 242 niveaux, ont été répartis en cinq groupes. Le diagnostic IRM a été comparé aux constatations opératoires afin d'évaluer de façon prospective la précision diagnostique de la classification IRM. Il n'y a pas eu d'exploration discale négative. Pour la distinction entre protrusion et autres types de hernie discale, la sensibilité, la spécificité et l'exactitude de l'IRM ont été respectivement de 92%, 91% et 92%. Pour la séquestration discale, la sensibilité a été de 92%, la spécificité de 99% et l'exactitude de 97%. En ce qui concerne l'extrusion sous-ligamentaire, on a noté une sensibilité de 71%, une spécifité de 82% et une exactitude de 79%, tandis que pour les extrusions trans-ligamentaires la sensibilité a été de 52%, la spécifité de 92% et l'exactitude de 79%. L'exactitude moyenne pour la prévision du type de hernie discale a donc été de 85%. L'IRM de haute résolution est donc très efficace pour la détection des lésions discales et leur classification.
    Notes: Summary Two hundred and eleven patients with lumbar disc herniation at 242 levels were divided into 5 groups by their appearances on magnetic resonance imaging (MRI), and the findings at operation were compared to assess the accuracy of the MRI classification. There were no negative explorations. There was 92% sensitivity, 91% specificity and 92% accuracy for MRI in distinguishing protruded discs from other forms of lumbar disc herniation. For sequestrated discs there was 92% sensitivity, 99% specificity and 97% accuracy. In the extruded subligamentous type there was 71% sensitivity, 82% specificity and 79% accuracy, and 52% sensitivity, 92% specificity and 81% accuracy in the extruded transligamentous type. The overall accuracy of MRI predicting the types of herniated lumbar intervertebral disc was 85%. High resolution MRI is sensitive in detecting disc disease and specific in characterizing various subgroups of disc herniation, especially those which are sequestrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194188
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  • 2
    Electronic Resource
    Electronic Resource
    Heteroepitaxial wurtzite and zinc-blende structure GaN grown by reactive-ion molecular-beam epitaxy: Growth kinetics, microstructure, and properties (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 189-204 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reactive-ion molecular-beam epitaxy has been used to grow epitaxial hexagonal-structure α-GaN on Al2O3(0001) and Al2O3(011¯2) substrates and metastable zinc-blende-structure β-GaN on MgO(001) under the following conditions: growth temperature Ts=450–800 °C; incident N+2/Ga flux ratio JN+2/JGa=1–5; and N+2 kinetic energy EN+2=35–90 eV. The surface structure of the α-GaN films was (1×1), with an ≈3% contraction in the in-plane lattice constant for films grown on Al2O3(0001), while the β-GaN films exhibited a 90°-rotated two-domain (4×1) reconstruction. Using a combination of in situ reflection high-energy electron diffraction, double-crystal x-ray diffraction, and cross-sectional transmission electron microscopy, the film/substrate epitaxial relationships were determined to be: (0001)GaN(parallel) (0001)Al2O3 with [21¯1¯0]GaN(parallel)[11¯00]Al2O3 and [11¯00]GaN(parallel)[12¯10]Al2O3, (21¯1¯0)GaN(parallel)(011¯2)Al2O3 with [0001]GaN(parallel)[01¯11]Al2O3 and [01¯10]GaN(parallel)[21¯1¯0]Al2O3, and (001)GaN(parallel)(001)MgO with [001]GaN(parallel)[001]MgO.Films with the lowest extended defect number densities (nd(approximately-equal-to)1010 cm−2 threading dislocations with Burgers vector a0/3〈112¯0(approximately-greater-than)) and the smallest x-ray-diffraction ω rocking curve widths (5 min) were obtained using Al2O3(0001) substrates, Ts≥650 °C, JN+2/JGa≥3.5, and EN+2=35 eV. Higher N+2 acceleration energies during deposition resulted in increased residual defect densities. In addition, EN+2 and JN+2/JGa were found to have a strong effect on film growth kinetics through a competition between collisionally induced dissociative chemisorption of N2 and stimulated desorption of Ga as described by a simple kinetic growth model. The room-temperature resistivity of as-deposited GaN films grown at Ts=600–700 °C with EN+2=35 eV increased by seven orders of magnitude, from 10−1 to 106 Ω cm, with an increase in JN+2/JGa from 1.7 to 5.0. Hall measurements on the more conductive samples yielded typical electron carrier concentrations of 2×1018 cm−3 with mobilities of 30–40 cm2 V−1 s−1. The room-temperature optical band gaps of α-GaN and β-GaN were 3.41 and 3.21 eV, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353882
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetic properties of sputtered Fe thin films: Processing and thickness dependence (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1233-1241 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure and magnetic properties of polycrystalline Fe films with thicknesses of 200–1000 A(ring) have been investigated. The films were prepared by rf sputtering onto SiO2 substrates. The investigation was prompted by the lack of data on sputtered Fe films in this thickness regime as well as disagreement in the data for evaporated films. In addition to thickness, substrate temperature and deposition pressure were varied to examine their effect on the microstructure. The film microstructure was characterized by x-ray diffraction, transmission electron microscopy, and Auger spectroscopy. The polycrystalline films did not display a strong preferred orientation and had average grain sizes of 60–85 A(ring). Surface oxide layers formed upon exposure to air ranged from 10 to 80 A(ring), the thicker oxides formed on films with lower density. Magnetic hysteresis measurements were made with a vibrating sample magnetometer. Below 1000 A(ring), porosity and surface oxidation result in reductions up to 25% in the saturation magnetization. An anomalous peak in coercivity at film thicknesses of 300–500 A(ring) was observed, which can be explained by the change in domain wall type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354926
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  • 4
    Electronic Resource
    Electronic Resource
    Processing-properties relationships in Fe3O4 thin films (abstract) : 37th annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6313-6313 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: As part of a fundamental study of interface magnetism in Fe/Fe3O4 multilayer systems, we have examined the magnetic properties of polycrystalline Fe3O4 thin films. Fe3O4 thin films, deposited by reactive evaporation and sputtering, have been previously studied because they serve as a precursor for the formation of γ-Fe2O3. The film thicknesses used in these studies have typically been greater than 100 nm. We have examined the magnetic properties and microstructure of Fe3O4 films with thicknesses less than 100 nm, a regime in which the magnetic properties have been reported to be strongly dependent on thickness.1 The films were deposited by rf sputtering. The processing variables examined include substrate material, substrate temperature, oxygen partial pressure, and film thickness. The microstructural origins of the observed coercivity and anisotropy will be discussed, as well as trends in the saturation behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352682
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  • 5
    Electronic Resource
    Electronic Resource
    Relaxation of vibrationally excited HCl molecules in the H2O–HCl collision complex (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 9521-9531 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The temperature dependence of the relaxation of HCl(v=1) by H2O in a complex-mode collision is studied in a semiclassical approach. The de-excitation probability takes a maximum value near room temperature, and it decreases logarithmically with increasing temperature. The dependence is nearly linear. Below room temperature, the relaxation becomes less efficient. This unusual temperature dependence is a result of the vibrational relaxation occurring in complex-mode collisions, which are dominated by large impact parameter interactions. The principal pathway for the removal of vibrational energy is the H–Cl oscillatory and librational motions along the O–H–Cl configuration. When these hindered motions gain the energy, they undergo transitions to free rotational states. The decreased energy transfer efficiency at low temperature is due to the slowing of rotational motions. Energy transfer to the O–Cl large-amplitude motion is of minor importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465486
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  • 6
    Electronic Resource
    Electronic Resource
    Application of a bridge circuit for an inductive critical current density measurement of superconducting thin films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2385-2386 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Recently, a new contactless Jc measurement technique by monitoring nonlinear responses from a coil mounted in the proximity of a superconducting film was reported by Classen et al. [Rev. Sci. Instrum. 62, 996 (1991)]. An improved method to measure the nonlinear inductive response is developed using an inductance bridge circuit, which discriminates the third-harmonic signal due to the nonlinearity from those of other origins. Moreover, in this technique, the phase of the third-harmonic signal can be used to determine the critical current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143941
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  • 7
    Electronic Resource
    Electronic Resource
    Symmetries of two-mode squeezed states (1993)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 34 (1993), S. 5493-5508 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is known that the symmetry of two-mode squeezed states is governed by the group Sp(4) which is locally isomorphic to the O(3,2) de Sitter group. It is shown that this complicated ten-parameter group can be regarded as a product of two three-parameter Sp(2) groups. It is shown also that two coupled harmonic oscillators serve as a physical basis for the symmetry decomposition. It is shown further that the concept of entropy is needed when one of the two modes is not observed. The entropy is zero when the system is uncoupled. The system reaches thermal equilibrium when the entropy becomes maximal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530318
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  • 8
    Electronic Resource
    Electronic Resource
    Growth of electropolymerized polyaniline thin films (1993)
    s.l. : American Chemical Society
    Chemistry of materials 5 (1993), S. 1474-1480 
    Details
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cm00034a017
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  • 9
    Electronic Resource
    Electronic Resource
    EFFECTS OF VARIOUS FRESH MEAT STORAGE METHODS ON THE COLOR OF COOKED GROUND PORK (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of muscle foods 4 (1993), S. 0 
    Details
    ISSN: 1745-4573
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of microbial growth in raw materials on cooked pork color were investigated. In two trials with sow meat held aerobically at 2C for 3 weeks, microbial load reached spoilage levels (107 cfu/g), pH increased to 6.46, and samples cooked to 71C had red exudate, shown by absorption spectroscopy to contain myoglobin and cytochrome c. Samples cooked to 82C also received high panel ratings for red color, due to red, flocculent precipitate in the exudate, but undenatured myoglobin levels were low. In sow meat held frozen or vacuum-packaged at 2C, pH after 3 weeks was 6.03 and 6.18, and plate counts were 104 and 107, respectively, but exudates after cooking were much less red. In five trials with fresh pork legs, total plate counts also reached 107 cfu/g by 3 weeks storage, and pH increased to 6.37, but cooked samples were not red. Higher myoglobin levels in sow meat probably accounted for the red color and level of undenatured myoglobin remaining after cooking of high pH, spoiled samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4573.1993.tb00491.x
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  • 10
    Electronic Resource
    Electronic Resource
    Improved confinement and stability in the DIII-D tokamak obtained through modification of the current profilef| (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2532-2539 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Improvement in both the energy confinement time and the achievable value of normalized beta is obtained by modifying the current density profile from the relatively broad shape obtained in standard tokamak discharges to a more peaked shape. The peaked current profile is produced with either a rapid negative ramp in the total plasma current or a rapid increase in the discharge elongation. Discharges have been obtained with βN=β/(I/aB)=6% mT/MA simultaneously with total energy confinement time two times the value predicted by L-mode scaling relations. Up to a factor of 1.8 improvement in the normalized thermal energy confinement time, τth/Ip, has been obtained in both L-mode and H-mode discharges. It is shown that the increase in confinement can be attributed to a local decrease in the thermal diffusivity that is correlated with a local increase in the poloidal magnetic field and the magnetic shear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860740
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